2003 Honda Civic Owner's Manual - Page 217

Transmission Fluid 5-speed Manual Transmission FILLER BOLT If Honda MTF is not available, you may use an SAE 10W-30 or 10W-40 viscosity motor oil with the API Certification seal that says ''FOR GASOLINE ENGINES'' as a temporary replacement. However, motor oil does not contain the proper additives and continued use can cause stiffer shifting. Replace as soon as it is convenient. The transmission should be drained and refilled with new fluid according to the time and distance recommendations in the maintenance schedule. Check the fluid level in the reservoirs monthly. There are up to two reservoirs, depending on the model. They are: Brake fluid reservoir (all models) Clutch fluid reservoir (manual transmission only) The brake fluid should be replaced according to the time and distance recommendations in the maintenance schedule. Correct Level Check the fluid level with the transmission at normal operating temperature and the car sitting on level ground. Remove the transmission filler bolt and carefully feel inside the bolt hole with your finger. The fluid level should be up to the edge of the bolt hole. If it is not, add Honda Manual Transmission Fluid (MTF) until it starts to run out of the hole. Reinstall the filler bolt and tighten it securely. 216 Maintenance